The Center's Program covers the following three mains areas of Cancer Biology: 1. Cancer Virology: This program includes: (a) an attack on many phases of the action of RNA tumor viruses; transcription and replication of the viral genome, its integration, its activation, and the mechanisms by which it exerts tumorigenic action. These studies are supplemented by studies on tumor virus enzymes in human leukemia. (b) studies on the genome of DNA cancer viruses, especially adenovirus, in the integrated state and on the mode of its expression. 2. Cancer Immunology: This program includes research: (a) on cell surface antigens on myeloma and other tumor cells; (b) on abnormal immunoglobulin related to leukemia; (c) on development of immunological responsiveness in thymus-lymphocytes. 3. Cellular and Developmental Biology of Cancer: This program includes: (a) studies on membrane proteins differentiating normal from "transformed" cells; (b) analysis of the expression of hemoglobin genes in Friend's leukemia cells and on the role of Friend's virus; (c) studies on the mechanisms of mutation in mammalian cells in relation to carcinogenesis. 4. Additional projects in the exploratory stage are: (a) structure of altered tRNA in cancer cell; (b) mechanism of dietary effects on the response to carcinogens; (c) template function of chromatin in cancer vs. normal cells.